var en_h = "rRseEfaqQtTdwWczxvg"; 
var reg_h = "[" + en_h + "]"; 

var en_b = { 
    k:0,o:1,i:2,O:3,j:4,p:5,u:6,P:7,h:8,hk:9,ho:10,hl:11,y:12,n:13,nj:14,np:15,nl:16,b:17,m:18,ml:19,l:20 
} 
var reg_b = "hk|ho|hl|nj|np|nl|ml|k|o|i|O|j|p|u|P|h|y|n|b|m|l"; 

var en_f = { 
    "":0,r:1,R:2,rt:3,s:4,sw:5,sg:6,e:7,f:8,fr:9,fa:10,fq:11,ft:12,fx:13,fv:14,fg:15,a:16,q:17,qt:18,t:19,T:20,d:21,w:22,c:23,z:24,x:25,v:26,g:27 
} 
var reg_f = "rt|sw|sg|fr|fa|fq|ft|fx|fv|fg|qt|r|R|s|e|f|a|q|t|T|d|w|c|z|x|v|g|"; 

var reg_exp = new RegExp("("+reg_h+")("+reg_b+")((?:"+reg_f+")(?=(?:"+reg_h+")(?:"+reg_b+"))|(?:"+reg_f+"))","g"); 

function toKorean(str) { 
    return str.replace(reg_exp,replace); 
} 

function replace(str,h,b,f) { 
    return String.fromCharCode(en_h.indexOf(h)*21*28 + en_b[b]*28 + en_f[f] + 44032); 
} 

temp = toKorean("잘못된 영어"); 
alert(temp);